Ground or road surface compacting machine

ABSTRACT

A self-propelled articulated compacting machine including three units connected in tandem. The middle unit is a propulsion unit having power driven roller means for moving the machine over the surface to be compacted. The end units are compactor assemblies of the vibratory roller type and these are pivotally connected to opposite ends of the propulsion unit. As the machine is propelled back and forth over the surface, a steering system controls the angular orientation of the lead compactor unit with reference to the propulsion unit, while the rear compactor unit is allowed to trail freely behind the propulsion unit in either direction of travel of the machine.

United States Patent 15] 3,683,763 Keppler et al. [451 Aug. 15, 1972 [54] GROUND OR ROAD SURFACE 2,987,975 6/ 1961 Seaman ..94/50 P CONIPACTING MACHINE 3,412,659 11/1968 Harbke ..94/5O R [72] Inventors: John E. Keppler; Jesse W. Harris,

[73] Assignee: Tampo Manufacturing Company,

San Antonio, Tex.

[22] Filed: July 27, 1970 [21] Appl. No.: 58,303

[52] US. Cl. ..94/50 R, 180/50 [51] Int. Cl ..E0lc 19/26 [58] Field of Search ..94/50; 180/20, 24, 150

[56] References Cited UNITED STATES PATENTS 3,259,036 7/ 1966 Peterson ..94/50 R 2,883,774 4/1959 Clifford ..180/50 X 3,326,312 6/1967 Buller ..94/50 R X 3,411,420 11/1968 Martin ..94/50 V both of San Antonio, Tex.

Primary Examiner-Jacob L. Nackenoff Attorney-Bums, Doane, Sweclcer & Mathis [57] ABSTRACT A self-propelled articulated compacting machine including three units connected in tandem. The middle unit is a propulsion unit having power driven roller means for moving the machine over the surface to be compacted. The end units are compactor assemblies of the vibratory roller type and these are pivotally connected to opposite ends of the propulsion unit. As the machine is propelled back and forth over the surface, a steering system controls the angular orientation of the lead compactor unit with reference to the propulsion unit, while the rear compactor unit is allowed to trail freely behind the propulsion unit in either direction of travel of the machine.

12 Claims, 6 Drawing Figures PATENTEDAus 15 m2 SHEET 1 OF 4 m m I Q L a INVENTORS 2 JOHN E KEPPLER JESSE 'w. HARRIS ,M

BY We a warm;

ATTORNEYS FIG. 2

PATENTEDAUE 15 I972 SHEET 2 BF 1 BACKGROUND OF THE INVENTION This invention relates to apparatus for compacting surfaces such as the ground or pavement surfaces. More particularly, this invention relates to a three-unit high capacity compacting machine.

Frequently it is desirable to increase the density or compaction of a ground surface, such as for example when fill is used to build a level terrain for shopping centers, parking lots, roadways and the like. Further, compaction is often desirable for finishing surfaces of asphalt composition which must support a relatively concentrated weight without becoming marred, indented or otherwise rendered unusable for the desired purpose.

In the past various devices have been useful to accomplish this compacting function, such as, for example, smooth or sheepfoot rotary roll machines which may be of the still or vibratory type. These machines are usually operated in a back and forth traversing manner so that the surface is suitably compacted for the desired purpose.

A frequent application for vibratory compactors is in roadway work. In this connection an earth bed is usually levelled and compacted. Upon this bed several layers of aggregate are spread and compacted with the size of the aggregate decreasing as the number of layers increases. The upper layer of aggregate is then finished or covered with one or more layers of asphalt or hot mix. Each of the layers of aggregate and hot mix requires a number of compacting passes to provide sufficient density to enable the resultant roadway to withstand the continual pounding of vehicles without becoming marred or otherwise rendered unsafe for high speed traffic.

The time required to treat a given surface section depends upon the length of the compaction roller used and upon the number of compacting sequences required to produce the desired increase in density. Both of these variables have been considered in searching for high capacity apparatus which could be used effectively in reducing the expense associated with compaction operations.

Extremely wide compacting units which would cover a maximum amount of surface area with each pass have not proved feasible. Such machines present structural problems in connection with the support means for the compaction rolls, and wide rolls tend to bridge areas which are thus left soft and result in holes beaten out when exposed to highway traffic. Another significant disadvantage with wide compacting machines is the difficulty of transporting an extremely wide load. Yet another serious deficiency inherent in very wide machines is their inability to form a roadway crown or raised portion in the center of a roadway as required by many state specifications to promote adequate drainage.

An alternative to an extremely wide machine would be a machine which would reduce the number of passes required by increasing the number of compacting rolls traversing the surface during each pass. However, such machines present problems not effectively solved heretofore with respect to maneuverability. In this connection, it is desirable that the machine be symmetrical in design so that it may be moved back and forth over the surface being compacting and steered with equal facility in either direction. The steering system also should operate in such a manner as to avoid lateral sliding or shifting of the compaction rolls as the machine is turned. Such siding, shifting or scuffing produces undesirable indentations in the surface being compacted.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore a general object of the invention to provide apparatus for compacting a ground surface which will obviate or minimize problems of the type previously described.

It is a specific object of the invention to provide a three unit tandum compacting machine capable of being maneuvered effectively over a surface without marring or scuffing the surface finish.

It is another object of the invention to provide a high capacity compacting apparatus which may be operated in either of two opposite directions with equal facility.

It is yet another object of the invention to provide a symmetric three-unit high capacity compacting machine which may be guided with equal facility by an operator in either of two opposite directions.

It is a further object of the invention to provide a symmetric three-unit high capacity compaction machine having a steering system wherein the lead unit is positively directed while the rear unit is permitted to trail freely notwithstanding the direction of travel of the compacting machine in either of two generally opposite directions.

It is a still further object of the invention to provide a symmetric three-unit high capacity compacting machine with a steering system wherein the operator may rotate the steering wheel in the direction of desired turning movement of the machine notwithstanding the direction of propulsion of the machine in either of two generally opposite directions.

An apparatus designed to accomplish the foregoing objects comprises a propulsion unit and first and second compactor assemblies pivotally connected to opposite ends of the propulsion unit. The propulsion unit carries an engine and includes ground engaging roller means driven by the engine. The compactor assemblies preferably include vibrator compaction rollers.

Steering rams are pivotally connected to the central propulsion unit and to the compactor assemblies and are actuated by a steering system to control turning movements of the machine. The steering system is such as to positively control the angular orientation of the leading compactor assembly with respect to the propulsion unit of the three-unit tandum machine while simultaneously permitting the rear compactor assembly to trail freely behind the propulsion unit notwithstanding the direction of travel of the machine in either of two generally opposite directions.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invention will become apparent from the following detailed description of preferred embodiments illustrated in the accompanying drawings, in which like numerals designate like parts:

FIG. 1 is a side elevational view of a three-unit tandum compacting machine according to an embodiment of the invention;

FIG. 2 is a plan view, partially in section, of the three-unit compacting machine shown in FIG. 1, disclosing in particular an embodiment of the hydraulic steering system of the invention;

FIG. 3 is a view of a two-position four-way valve partially in section, disclosing the valve positioned in a crossing mode;

FIG. 4 is a view of a two-position four-way valve partially in section, disclosing the parallel mode of the four-way valve used in the invention;

FIG. 5 is a schematic view of a hydraulic steering system for a self-propelled three-unit articulated compacting machine utilizing a single steering ram positioned between the drive unit and each of the compactor units; and

FIG. 6 is a side elevational view of a self-propelled articulated compacting machine wherein the central unit is provided with a compacting roller which provides the tractive effort to drive the compacting machine and serves to further compact the ground surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS General Structure The three-unit compacting machine shown in FIG. 1 includes a central propulsion unit 10 having a tractor frame 11 supported on roller means in the form of two spaced parallel wheels 12 and 14 which engage the surface 15 to be compacted. These wheels, and therefore the machine as a whole, are propelled in either a direction generally to the left or to the right as viewed in FIGS. 1 and 2 by an engine generally designated by reference character 16, which engine may be of any suitable type.

Pivotally attached to the left end of the propulsion unit as viewed in FIGS. 1 and 2 is a first compactor assembly or unit 18. Compactor assembly 18 is pivotally disposed about a generally vertical axis 20 by means of a generally U-shaped connecting yoke 22 having end portions thereof pivotally received within a bifurcated bracket member 24 which is fixedly connected to tractor frame 11. A pair of heavy duty bearing pins 26 are disposed through apertures in the bifurcated bracket and connecting yoke to pivotally secure the two members together. This generally vertical pivotal connection enables the first compactor unit 18 to be pivoted with respect to the propulsion unit 10 in a manner which will be more fully discussed hereinafter.

The first compactor unit 18 includes a compaction roller 28 and a generally U-shaped support frame 30. In order to enhance the compacting capabilities of the machine the roller preferably is vibrated as it traverses the ground surface 15. This is accomplished by rotatable eccentric means positioned within the interior of the roller 28, the roller being resiliently suspended within the support frame 30. A drive motor 32 for the eccentric is carried by the frame 30 as best seen in FIG. 2. For more detailed descriptions of suitable vibratory compactor assemblies reference may be had to US. Pat. No. 3,411,420 and US. Pat. Ser. No. 812,144, now US. Pat. No. 3,605,583, both assigned to the assignee of the present invention, the disclosures of which are incorporated herein by reference as though set forth at length.

A second compactor assembly or unit 34 is disposed at the right end of the propulsion unit 10 as viewed in FIGS. 1 and 2. This compactor unit 34 includes a vibratory roller 36 mounted within a support frame 38 and may be essentially identical to the compactor unit 18 connected to the opposite end of the propulsion unit 10. Compactor unit 34 is pivotally connected about mutually perpendicular axes 40 and 42. A first yoke bracket 44 fixed to the frame 38 is pivotally connectedto a bifurcated bracket 46 by a bearing pin 48 disposed along the generally horizontal axis 40. A second yoke bracket 50 attached to the propulsion unit frame 1 l is pivotally connected to the opposite end of the bifurcated bracket 46 by bearing pins 52 extending along the generally vertical axis 42. The pivotal connection at 40 enables the compacting machine to maintain engagement with an undulating ground surface being compacted, while the generally vertical pivotal connection at 42 enables the second compactor unit 34 to be pivoted with respect to the propulsion unit 10 in a manner which will be more fully described hereinafter. Steering System The steering system for the articulated three-unit compacting machine includes a steering wheel 53 disposed generally transverse to the longitudinal dimension of the machine directly in front of a laterally facing operators seat or station the back of which is indicated at 54 in FIG. 1. Therefore, the machine from the operators physical standpoint may be operated in a direction to the left or to the right as viewed in FIG. 2 with equal facility.

The steering wheel 53 is fixed to a control shaft 55 of a power steering hydraulic fluid flow controller 56 of a type illustrated and described in detail in US. Pat. No. Re. 25,126.

The controller 56 includes a housing 57 having one pair of ports therein connectedto a power assist circuit and another pair of ports connected to a steering circuit. The power assist circuit includes a sump 60, a filter 62, a pump 64, a fluid delivery line 66 and a return line 68. The steering circuit, to be described in detail below, includes lines 70 and 72 connected to the other pair of controller housing ports.

Although the internal structure of the controller 56 need not be described here, it will be useful to note certain operational characteristics of the unit. The power assist circuit pump 64 operates on a continuous basis when the machine is in use, but fluid flow through the lines 70 and 72 of the steering circuit occurs only when the steering wheel 53 is being rotated. Rotation of the shaft 55 in a counterclockwise direction (FIG. 2) causes fluid to flow out of the port connected to line 70 and return through the port connected to line 72. Rotation of the shaft 55 in the opposite direction causes fluid to flow out of the port connected to line 72 and return through the port connected to line 70. In each instance the volume of fluid delivered to the steering circuit is proportioned to the angular extent of the rotational movement imparted to the steering wheel 53 by the machine operator.

For a more detailed description of the fluid controller 56 and its operation, reference may be had to the aforesaid U.S. Pat. No. Re. 25,126, the disclosure of which is incorporated herein by reference as though set forth at length.

Following line 70 from the fluid controller 56, it will be seen that the line is connected directly into a'twoposition four-way valve indicated by generalreference character 74 in FIG. 2. Valve 74 is illustrated in greater detail in FIGS. 3 and 4 and will be discussed more fully hereinafter. Line 70 leads directly into port A in the four-way valve. Generally opposite port A is port B which is in fluid communication through conduit 76 with piston and cylinder steering assemblies 78 and 80 at the right end of the propulsion unit as viewed in FIG. 2

The reciprocable rods 82 and 84 of the steering assemblies 78 and 80, respectively, are pivotally connected at their ends to torque arms '86 and 88 which extend laterally from the bifurcated bracket 46. The bases of the assemblies 78 and 80 are in like manner pivotally connected to the central drive unit 10. It will be appreciated that an extension or retraction of rod 82 and a converse retraction or extension of rod 84 will pivot the second compacting unit 34 about the axis 42 in a generally counterclockwise or clockwise direction as viewed in FIG. 2.

Referring again to conduit 76, it will be seen that a tee joint 94 is provided in the conduit 76 adjacent the base of the steering cylinder 78 for delivering fluid into the base thereof and extending the rod 82 when line 76 is pressurized. The end of line 76 is connected to the forward portion of the steering cylinder 80 in such a manner as to deliver fluid into the forward portion thereof when line 76 is pressurized. Thus, it will be realized that when line 76 is hydraulically pressurized, rod 82 will extend and rod 84 will retract, thus pivoting compactor unit 34 in the position generally indicated in phantom at 90.

The second line 72, connected to the fluid controller 56, leads into an open cross 96. One branch of the cross 96 connects into a line 98 in fluid communication with the piston and cylinder assemblies 78 and 80, by way of a tee joint 100 at the base of the steering cylinder80 and a direct tap into the forward portion of the steering cylinder 78. It will be noted that these connections are opposite to those made for the line 76. Therefore, if line 98 is hydraulically pressurized, rod 84 will extend while the rod 82 will retract, thus pivoting the compacting unit 34 about the axis 42 in a generally clockwise direction as viewed in FIG. 2 to a position indicated generally by phantom lines at 92.

Another branch in the open cross 96 connects into line 120. Line 120 leads directly to port D in the fourway valve 74. Opposite port D is a port C which as a further hydraulic line 122 directly connected thereto. Line 122 leads to a pair of piston and cylinder steering assemblies 102 and 104 at the left end of the propulsion unit as viewed in FIG. 2.

Reciprocable rods 106 and 108 if the steering assemblies 102 and 104 respectively are pivotally connected at their ends to torque arms 110 and 112 which extend laterally from the connecting yoke 22 on the left compactor unit 18. The bases of the steering assemblies 102 and 104 are pivotally connected to the central drive unit 10. It will be appreciated that an extension or retraction of rod 106 and a converse retraction or extension of rod 108 will pivot the compactor unit 18 about the axis 20 in a generally clockwise or counterclockwise direction as viewed in FIG. 2.-

Referring again toconduit 122, it will be seen that a tee joint 124 is provided therein adjacent the base of the steering cylinder 104 for delivering fluid into the base thereof and extending rod. 108 when line 122 is pressurized. The end of line 122 is connected into the forward portion of the steering cylinder 102 in such a manner so as to deliverfluid into the forward portion thereof when line 122 is pressurized. Thus, it will be realized that if line 122 is hydraulically pressurized, rod 108 will extend and rod 106 will retract to rotate compactor unit 18 in the general position indicated in phantom at 126.

Another branch of the open cross 96 connects into a line 114 in direct fluid communication with piston and cylinder steering assemblies 102 and 104 by means of a tee joint 116 at the base of the steering cylinder 102 and a direct tap into the forward portion of the steering cylinder 104. It will be noted that these connections are opposite to those made for the line 122. Therefore, if line 114 is hydraulically pressurized, rod 106 will ex tend and rod 108 will retract to pivot the compacting unit 18 about the axis 20 in a generally clockwise direction as viewed in FIG. 2 to a position generally indicated by phantom lines at l 18.

Referring now to FIGS. 3 and 4, the twoposition four-way valve 74 is shown broken away to disclose the internal structure thereof. It will be seen that lines 70, 76, 122 and connect directly into ports A, B, C and D, respectively. The internal ways 128, 130, 132 and 134 in the housing structure 136 are designed to open into a cylindrical cavity 138 the housing. The way 128 is provided with a normally ofiset branch 146 which also leads into the central cavity 138 in the valve housing. This cavity is filled by a spool 140 in intimate sliding engagement therewith. The spool 140 is provided with a pair of peripheral recesses 142 and 144.

FIG. 3 illustrates one position of the spool 140. This position is one in which the peripheral recess 142 establishes fluid communication between the ways 134 and while the peripheral recess 144 establishes fluid communication between the ways 146 and 132. In this position, therefore, the valve is in a crossing posture in that port A communicates with port C and port B cormnunicates with port D.

A second position is illustrated in FIG. 4. Here the position of the spool is such as to establish through recess 142 fluid communication between the ways 128 and 130, while the cylindrical recess 144 establishes fluid communication between the ways 134 and 132. Thus, in the position shown in FIG. 4, the valve is in a parallel posture in that port A is in fluid communication with port B and port D is in fluid communication with port C.

In order to prevent unintended displacement of the inner spool 140 from the crossing configuration as shown in FIG. 3 or the parallel configuration shown in FIG. 4, a pair of peripheral channels 148 and 150 are fashioned in the spool at one end thereof. A spring biased ball stop 152 is provided in the valve housing 136 to engage either of the channels 150 or 148 and exert detenting forces for retaining the valve in the desired posture. In order to maintain hydraulic fluid integrity through the four-way valve, a suitable hydraulic seal 158 is positioned in each end of the valve housing 136.

Actuation of the valve may be accomplished by a suitable device which is responsive to a reversal of the direction of propulsion of the unit 10. In this connection, for illustrative purposes, a solenoid arrangement 154 is shown wherein a two-throw switch 156 may be connected to a drive unit propulsion lever 155, such that the valve spool 140 may be positioned in a parallel or crossing posture depending upon the direction of actuation of the propulsion lever. It will be understood of course that this lever 155 is coupled in a suitable fashion to the means for driving the wheels 12 and 14 so that, in one position of the lever, the wheels will be rotated in a direction to move the machine to the left in FIG. 2, and in the other position of the lever, the wheels will be rotated in a direction to move the machine to the right in FIG. 2.

Operation of the machine Referring now to FIG. 2, let it be assumed that the three-unit high capacity compacting machine is being propelled in a left to right direction. Under such conditions, the lever 155 will be in a position to cause the solenoid 154 to position the valve spool 140 as illustrated in FIG. 4. Should the operator now desire to pivot the leading compactor assembly 34 toward the position shown in phantom at 92, so as to steer the machine to the right of its longitudinal line of travel, he may rotate the steering wheel 53 in a clockwise direction. The controller 56 is so connected in the system that clockwise rotation of the shaft 55 (as viewed from above) serves to meter fluid under pressure out of the port connected to the line 72.

Note in this connection that, from the perspective of the machine operator whose eyes are located generally above both the steering wheel 53 and the pivot axis about which steering movements of the compactor assembly 34 takes place, the directions of rotation of the steering wheel 53 and of pivoting of the compactor assembly 34 are the same. That is, both are clockwise in this instance.

As the steering wheel is rotated clockwise, hydraulic fluid will travel in line 72 in proportion to the amount of rotation of the steering wheel to the open cross 96 and through the line 98, to enter the cylinder 80 at its base through tee fitting 100 and to enter the steering cylinder 78 at the forward portion thereof. As previously discussed, hydraulic fluid entering steering cylinders 78 and 80 in this manner will induce pivotal movement of the compactor unit 34 about the generally vertical axis 42 toward the position represented in phantom by 92 and the vehicle will thus turn in the direction of rotation of the steering wheel.

In order that side scuffing of the articulated machine components may be avoided, it is necessary that the trailing compactor unit, i.e., the unit 18 when the machine is travelling in the left to right direction, be free to trail idly behind the propulsion unit 10. In other words, hydraulic fluid from steering assemblies 102 and 104 must be free to interchange back and forth. In this connection it will be readily appreciated that these hydraulic fluid cylinders are in direct fluid communication with each other through the open cross 96 and the two-position four-way valve 74 in its parallel posture.

Thus, the rear compacting unit 18 will be free to trail the driving unit.

If it is desired to turn the vehicle in the counterclockwise direction as the compacting machine is travelling from left to right, the operator will rotate the wheel in a counterclockwise direction to deliver hydraulic fluid to the line leading directly to port A of the two-position four-way valve 74. As previously mentioned, during the vehicles translation in a left to right direction, the valve 74 will be in a parallel posture (FIG. 4). Hence, the hydraulic fluid will exit from port B into line 76 to flow behind the piston of the steering assembly 78 and in front of the piston of the steering assembly 80 to pivot the lead compactor unit 34 about the generally vertical axis 42 in a direction toward the position generally depicted in phantom at 90. The rear steering units 102 and 104 will again be connected together, or fluid short circuited, through the open cross 96 and the parallel posture of valve 74, so that the trailing compactor unit 18 will be free to follow idly behind the propulsion unit 10.

When the desired left to right movement of the compacting machine has been completed and a further compacting pass is desirable, the operator switches the drive unit propulsion lever 155 to an opposite position so that the propulsion unit 10 will drive the machine in a right to left manner. This switching will automatically actuate the solenoid 154 to position the valve spool 140 as shown in FIG. 3 (the crossing posture of the valve 74).

The effect of switching the valve from its parallel posture (FIG. 4) to its crossing posture (FIG 3) is to couple the steering wheel 53 with the steering assemblies 102 and 104 for the lead compactor assembly 18 and uncouple the steering wheel 53 from the steering assemblies 78 and 80 for the trailing compactor assembly 34. In this connection it is note worthy that the shaft 55 connected to the steering wheel 53 is endlessly rotatable in either direction and its angular position bears no fixed relation to angular position of the steered compactor assembly. With a controller 56 of the type disclosed in U.S. Pat. No. Re. 25,126, it is movement, rather than angular position, of the control shaft which produces effects on fluid flow.

Therefore, at the movement of switching the valve 74 from its parallel to its crossing posture, the system becomes indifferent to the angular position of the compactor unit 34 and assumes full control over the angular position of the other compactor unit 18 without regard to where this unit may be at the time. That is, even if the control shaft 55 had just prior to a propulsion change, completed a counterclockwise rotation sufficient to position the compactor assembly 34 at in FIG. 2, it could be turned counterclockwise again immediately after the propulsion direction change to pivot the compactor assembly 18 toward the position indicated at 126.

As previously indicated, counterclockwise rotation of the steering wheel 53 and control shaft 55 will meter fluid from the fluid controller 56 to line 70. Fluid under pressure is thus delivered through ports A and C of the valve 74 to the line 122 connected into the rear portion of steering cylinder 104 and the front portion of steering cylinder 102, so that the lead compactor unit 18 will be pivoted in a counterclockwise direction toward the position shown in phantom at 126.

In order to prevent scuffing or marring of the surface being compacted, the former lead unit 34 which is now the trailing unit must be free to trail in a neutral condition. In this connection it will be appreciated that if the steering assemblies 78 and 80 are in direct fluid communication, the rear compacting unit 34 will be free to trail. To this end line 76 connects with line 120 through the valve 74, which is in its crossed posture and line 120 is in fluid communication with line 98 through the open cross 96.

If it is desired to direct the articulated compacting machine in a clockwise direction as the unit is travelling from right to left, the operator will rotate the steering wheel 53 in a clockwise direction or into the intended direction of turn. Clockwise rotation of the wheel 53 will meter fluid into line 72, through the cross 96, and into the line 114 which leads to the rear portion of steering assembly 102 and the forward portion of steering assembly 104. Hydraulic fluid delivered to the steering assemblies in this manner will induce a pivoting movement of the compacting unit 18 toward the piston shown in phantom at 118 in FIG. 2. During such movement, the steering assemblies 78 and 80 will be in direct fluid communication through the open cross 96 and the valve 74. Thus, the rear compacting unit 34 will be free to trail in a neutral posture, and marring of the surface being compacted will be eliminated or minimized.

While the invention has been discussed particularly with reference to a pair of steering assemblies at each end of the propulsion unit 10, it will be appreciated by those skilled in the art that a single steering assembly at each end of the propulsion unit could be designed to accomplish similar results. In this connection attention is invited to FIG. illustrating schematically a hydraulic system for accomplishing steering with two assemblies. The preceding discussion of the system shown in FIG. 2 and the components forming that system is generally applicable to the two assembly system shown in FIG. 5, and like numerals have been used to designate like parts in the two views. Since the system of FIG. 5 differs from that of FIG. 2 only be reason of its omission of the piston-cylinder units 80 and 104 and the related hydraulic connections, the operation of the system of FIG. 5 will be evident from what has already been said with reference to the FIG. 2 system.

Additionally, it will be appreciated that the articulated compacting machine, as illustrated in FIGS. 1 and 2, relies for tractive effort upon wheels 12 and 14. It is feasible however to further increase the capacity of the compacting machine by replacing the wheels 12 and 14 v with a third compaction roller 160 as depicted in FIG. 6. This roller 160 may be a vibratory compaction roller, if desired.

Thus it will be seen that in following the present invention an improved high capacity compacting machine is provided. Particularly significant is the provision of a three-unit tandum compacting machine which may be guided in either of two opposite directions with equal facility by an operator positioned approximately transverse to the direction of travel of the machine in either direction.

Further, it is significant that the lead compacting unit is positively steered while the rear compacting unit is free to trail in a neutral condition and thus scuffing of the compacted surface as the vehicle is turned is avoided.

Another significant advantage of the invention is that the operator may rotate the steering wheel into the direction of turn of the compacting vehicle notwithstanding the direction of motion of the compacting machine.

Although the invention has been described with reference to certain illustrated embodiments, it will be appreciated by those skilled in the art that additions, modifications, substitutions, deletions and other changes not specifically described herein may be made which will fall within the purview of the appended claims.

What is claimed is:

l. A machine movable back and forth over a surface to be compacted comprising:

a propulsion unit including roller means for contacting said surface and reversible drive means for driving said roller means in either direction to propel the machine longitudinally along said surface;

first and second compactor assemblies connected respectively to opposite longitudinal end portions of said propulsion unit for pivotal movements relative thereto about axes vertical to said surface and each including roller means rollable over said surface in response to propelling rotation of said propulsion unit roller means in either of said directions;

first and second compactor assembly pivoting means connected respectively between said first and second compactor assemblies and said propulsion unit; and Y means connected to said first and second compactor assembly pivoting means for controlling the pivotal movements of whichever one of said first and second compactor assemblies is at a given time leading said propulsion unit in the direction of travel thereof while permitting free pivotal movements of whichever one of said first and second compactor assemblies is at a given time trailing said propulsion unit in the direction of travel thereof.

2. A machine according to claim 1 wherein said roller means of said first and second compactor assemblies are vibratory compaction rollers.

3. A machine according to claim 2 wherein said roller means of said propulsion unit includes a vibratory compaction roller.

4. A machine according to claim 1 wherein said roller means of said propulsion unit comprises:

two spaced parallel wheels.

5. A machine movable back and forth over a surface to be compacted comprising:

a propulsion unit including roller means for contact ing said surface and reversible drive means for driving said roller means in either direction to propel the machine longitudinally along said surface;

first and second compactor assemblies connected respectively to opposite longitudinal end portions of said propulsion unit for pivotal movements relative thereto about axes vertical to said surface and each including roller means rollable over said surface in response to propelling rotation of said propulsion unit roller means in either of said directions; and

steering means connected between said propulsion unit and said first and second compactor assemblies for controlling the pivotal movements of whichever one of said assemblies is at a given time leading said propulsion unit in the direction of travel thereof while permitting free pivotal movements of whichever one of said assemblies is at a given time trailing said propulsion unit in the direction of travel thereof including,

a control element adapted to be manipulated by an operator of the machine for altering the path of the machine over said surface,

first and second assembly pivoting means connected respectively to said first and second compactor assemblies, and

means for operably connecting said control element to said first assembly pivoting means and simultaneously permitting free pivotal movement of said second assembly pivoting means when said first compactor assembly is leading said propulsion unit in the direction of travel of the machine and for operably connecting said control element to said second assembly pivoting means and simultaneously permitting free pivotal movement of said first assembly pivoting means when said second compactor assembly is leading said propulsion unit in the direction of travel of the machine.

6. A machine according to claim additionally comprising a laterally facing operators seat on said propulsion unit; and wherein said control element is located adjacent said seat.

7. A machine according to claim 5 wherein said assembly pivoting means are hydraulically operated.

8. A machine according to claim 7 wherein said first and second assembly pivoting means each comprises a pair of hydraulic ram units positioned respectively on opposite sides of the pivotal connection between said propulsion unit and the adjacent compactor assembly and being pivotally connected between such compactor assembly and said propulsion unit.

9. A machine according to claim 7 wherein said means for operatively connecting said control element to said assembly pivoting means includes:

means connected to said control element for causing hydraulic fluid flow in response to manipulation of said element;

fluid circuit means interconnecting the last mentioned means with said assembly pivoting means and comprising valve means having a first condition in which fluid flow in response to manipulation of said element is directed to said first assembly pivoting means while said second assembly pivoting means is fluid short circuited and a second condition in which fluid flow in response to manipulation of said element is directed to said second assembly pivoting means while said first assembly pivoting means is fluid short circuited; and

means operatively connected to said valve means for causing it to assume said first condition when said propulsion unit is being propelled in a direction such that said first compactor assembly leads in the direction of travel of the machine and for causing said valve means to assume said second condition when said propulsion unit is being propelled in ?e$i3i"fi2dii2 i'lf iiil cififi r tl'a'i fir rife machine.

10. A machine according to claim 9 wherein said fluid circuit means includes:

a valve housing having four fluid ports therein; fluid conduit means connecting a first one of said ports to one side of said means for causing hydraulic fluid flow in response to manipulation of said control element,

a second one of said ports to one side of said first assembly pivoting means,

a third one of said ports to one side of said second assembly pivoting means, and

a fourth one of said ports to the opposite sides of said first and second assembly pivoting means and to the opposite side of said means for causing hydraulic fluid flow in response to manipulation of said control element; and means within said valve housing for fluidly connecting said first port to said second port and simultaneously connecting said third port with said first port in a first position thereof and for fluidly connecting said first port with said third port and simultaneously connecting said second port with said fourth port in a second position thereof. 11. A machine according to claim 9 wherein said control element is endlessly rotatable in either direction and wherein said means connected to said control element for causing hydraulic fluid flow includes:

a housing having first and second ports therein connected to said fluid circuit means;

means operatively connected to said control element for delivering fluid flow out of said housing through one of said ports during rotation of said control element; and

flow direction control means operatively connected to said control element for directing said fluid flow out of said housing through said first port upon rotation of said control element in one direction and for directing said fluid flow out of said housing through said second port upon rotation of said control element in the opposite direction.

12. A machine according to claim 11 wherein said fluid circuit means so interconnects said ports with said assembly pivoting means that rotation of said control element in one direction causes either counterclockwise pivoting of said first compactor assembly or clockwise pivoting of said second compactor assembly depending upon whether said valve means is in its first or second condition. 

1. A machine movable back and forth over a surface to be compacted comprising: a propulsion unit including roller means for contacting said surface and reversible drive means for driving said roller means in either direction to propel the machine longitudinally along said surface; first and second compactor assemblies connected respectively to opposite longitudinal end portions of said propulsion unit for pivotal movements relative thereto about axes vertical to said surface and each including roller means rollable over said surface in response to propelling rotation of said propulsion unit roller means in either of said directions; first and second compactor assembly pivoting means connected respectively between said first and second compactor assemblies and said propulsion unit; and means connected to said first and second compactor assembly pivoting means for controlling the pivotal movements of whichever one of said first and second compactor assemblies is at a given time leading said propulsion unit in the direction of travel thereof while permitting free pivotal movements of whichever one of said first and second compactor assemblies is at a given time trailing said propulsion unit in the direction of travel thereof.
 2. A machine according to claim 1 wherein said roller means of said first and second compactor assemblies are vibratory compaction rollers.
 3. A machine according to claim 2 wherein said roller means of said propulsion unit includes a vibratory compaction roller.
 4. A machine according to claim 1 wherein said roller means of said propulsion unit comprises: two spaced parallel wheels.
 5. A machine movable back and forth over a surface to be compacted comprising: a propulsion unit including roller means for contacting said surface and reversible drive means for driving said roller means in either direction to propel the machine longitudinally along said surface; first and second compactor assemblies connected respectively to opposite longitudinal end portions of said propulsion unit for pivotal movements relative thereto about axes vertical to said surface and each including roller means rollable over said surface in response to propelling rotation of said propulsion unit roller means in either of said directions; and steering means connected between said propulsion unit and said first and second compactor assemblies for controlling the pivotal movements of whichever one of said assemblies is at a given time leading said propulsion unit in the direction of travel thereof while permitting free pivotal movements of whichever one of said assemblies is at a given time trailing said propulsion unit in the direction of travel thereof including, a control element adapted to be manipulated by an operator of the machine for altering the path of the machine over said surface, first and second assembly pivoting means connected respectively to said first and second compactor assemblies, and means for operably connecting said control element to said first assembly pivoting means and simultaneously permitting free pivotal movement of said second assembly pivoting means when said first compactor assembly is leading said propulsion unit in the direction of travel of the machine and for operably connecting said control element to said second assembly pivoting means and simultaneously permitting free pivotal movement of said first assembly pivoting means when said second compactor assembly is leading said propulsion unit in the direction of travel of the machine.
 6. A machine according to claim 5 additionally comprising a laterally facing operator''s seat on said propulsion unit; and wherein said control element is located adjacent said seat.
 7. A machine according to claim 5 wherein said assembly pivoting means are hydraulically operated.
 8. A machine according to claim 7 wherein said first and second assembly pivoting means each comprises a pair of hydraulic ram units positioned respectively on opposite sides of the pivotal connection between said propulsion unit and the adjacent compactor assembly and being pivotally connected between such compactor assembly and said propulsion unit.
 9. A macHine according to claim 7 wherein said means for operatively connecting said control element to said assembly pivoting means includes: means connected to said control element for causing hydraulic fluid flow in response to manipulation of said element; fluid circuit means interconnecting the last mentioned means with said assembly pivoting means and comprising valve means having a first condition in which fluid flow in response to manipulation of said element is directed to said first assembly pivoting means while said second assembly pivoting means is fluid short circuited and a second condition in which fluid flow in response to manipulation of said element is directed to said second assembly pivoting means while said first assembly pivoting means is fluid short circuited; and means operatively connected to said valve means for causing it to assume said first condition when said propulsion unit is being propelled in a direction such that said first compactor assembly leads in the direction of travel of the machine and for causing said valve means to assume said second condition when said propulsion unit is being propelled in a direction such that said second compactor assembly leads in the direction of travel of the machine.
 10. A machine according to claim 9 wherein said fluid circuit means includes: a valve housing having four fluid ports therein; fluid conduit means connecting a first one of said ports to one side of said means for causing hydraulic fluid flow in response to manipulation of said control element, a second one of said ports to one side of said first assembly pivoting means, a third one of said ports to one side of said second assembly pivoting means, and a fourth one of said ports to the opposite sides of said first and second assembly pivoting means and to the opposite side of said means for causing hydraulic fluid flow in response to manipulation of said control element; and means within said valve housing for fluidly connecting said first port to said second port and simultaneously connecting said third port with said first port in a first position thereof and for fluidly connecting said first port with said third port and simultaneously connecting said second port with said fourth port in a second position thereof.
 11. A machine according to claim 9 wherein said control element is endlessly rotatable in either direction and wherein said means connected to said control element for causing hydraulic fluid flow includes: a housing having first and second ports therein connected to said fluid circuit means; means operatively connected to said control element for delivering fluid flow out of said housing through one of said ports during rotation of said control element; and flow direction control means operatively connected to said control element for directing said fluid flow out of said housing through said first port upon rotation of said control element in one direction and for directing said fluid flow out of said housing through said second port upon rotation of said control element in the opposite direction.
 12. A machine according to claim 11 wherein said fluid circuit means so interconnects said ports with said assembly pivoting means that rotation of said control element in one direction causes either counterclockwise pivoting of said first compactor assembly or clockwise pivoting of said second compactor assembly depending upon whether said valve means is in its first or second condition. 